A brake test method is disclosed for use in testing the operation of a brake of a drive system comprising a motor operable to drive a pair of drive shaft arrangements for rotation, an inboard brake associated with the motor, a first outboard brake associated with an end part of a first one of the drive shaft arrangements, and first and second outboard position sensors associated with the end parts of respective ones of the drive shaft arrangements, the method comprising the steps of applying the first outboard brake, operating the motor to apply a torque to the first drive shaft arrangement, applying the inboard brake, de-activating the motor, and using the output of the second outboard position sensor in determining an operating status of the inboard brake and/or first outboard brake.